// 代码来源：https://github.com/xpl/crx-hotreload/edit/master/hot-reload.js
const filesInDirectory = dir =>
  new Promise(resolve =>
    dir.createReader().readEntries(entries =>
      Promise.all(
        entries
          .filter(e => e.name[0] !== '.')
          .map(e => (e.isDirectory ? filesInDirectory(e) : new Promise(resolve => e.file(resolve))))
      )
        .then(files => [].concat(...files))
        .then(resolve)
    )
  )

const timestampForFilesInDirectory = dir =>
  filesInDirectory(dir).then(files => files.map(f => f.name + f.lastModifiedDate).join())

const reload = () => {
  window.chrome.tabs.query(
    {
      active: true,
      currentWindow: true,
    },
    tabs => {
      // NB: see https://github.com/xpl/crx-hotreload/issues/5
      if (tabs[0]) {
        window.chrome.tabs.reload(tabs[0].id)
      }
      window.chrome.runtime.reload()
    }
  )
}

const watchChanges = (dir, lastTimestamp) => {
  timestampForFilesInDirectory(dir).then(timestamp => {
    if (!lastTimestamp || lastTimestamp === timestamp) {
      setTimeout(() => watchChanges(dir, timestamp), 1000) // retry after 1s
    } else {
      reload()
    }
  })
}

window.chrome.management.getSelf(self => {
  if (self.installType === 'development') {
    window.chrome.runtime.getPackageDirectoryEntry(dir => watchChanges(dir))
  }
})
